As is well known, rendering plants emit offensive odors. These are required to be eliminated by air pollution regulations of the various governmental jurisdictions wherein a plant is located. Many proposals have been made to eliminate these odors, ranging from a simple water-washing procedure to chemical treatment of the plant off-gases.
A number of these proposals involve absorption treatment in packed towers. While effective, they nevertheless have certain deficiencies in that they have relatively short reaction time, are subject to fouling, and because of their significant pressure drops require relatively large horsepower fans. The presence of packing resulted in the necessity for stronger construction and in a heavier structure, which in turn limits the situs where the purification plant may be located.
Other proposed processes employ spray chambers wherein the droplet size is relatively large, resulting in relatively small droplet area-to-volume ratios. In general, the larger this ratio the greater the total reaction surface and the more effective the scrubbing action.
In contrast to the relative high cost of the prior art methods, the present invention provides a relatively inexpensive system costing a fraction as much for treating offensive gases and vapors from various processing plants. The component elements required for the invention are simple and of lightweight construction which reduces the cost and permits greater flexibility in physical location of the treating system.
Among the objects of the present invention are:
1. To provide a relatively inexpensive and improved method for the removal of foul odors emanating from certain industrial operations such as rendering process plants.
2. To condense the entire condensable fraction of vapors emanating from the plant operation prior to any subsequent chemical treatment.
3. To treat the uncondensed vapors in a non-packed spray tower employing very fine droplets of chemical reactants having a high surface-to-volume ratio.
4. To provide a relatively long reaction time within the spray tower for the uncondensed vapors containing malodorous constituents.
5. To introduce the uncondensed vapors at the top of the spray tower, and remove the treated vapors from the bottom of the tower.
6. To provide a fan to remove the treated vapors from the spray tower.
7. To provide an inlet to admit ambient air into the treated vapors where they exit from the spray tower to lower the dew point.
8. To provide a spray tower which has a very low pressure drop.
9. To provide a spray tower system where fouling is significantly lessened.
10. To provide a spray tower of relatively light weight fiberglass reinforced resin which can be mounted on a roof with but minor structural alterations.
Further objects will become apparent from the specification and claims following.